The Pantheon: From Antiquity to the Present

by Unknown

  We need to recall that scarcely more than a half century after the consecration of the Pantheon to Saint Mary and All Martyrs, the Byzantine emperor Constans II organized the removal of the bronze tiles from the dome of the edifice in AD 663 and shipped them to Syracuse.1 In the eighth century, Pope Gregory III replaced those tiles with lead plates. In 1270, a bell tower was installed atop the ridge of the pediment, in keeping with the increasingly common practice of marking the hours and church rituals throughout Rome in the thirteenth century.2 With time, ancient buildings around the Pantheon were despoiled of their materials, many crumbling to the ground, while shops, vendors’ stalls, and habitations were built against surviving remains. The process, deeply entrenched in the history of the site, continued well after prohibitions against such encroachments were published. Because the hastily constructed shacks and stalls were usually built of wood, fire was an ever-present danger, with falling timbers capable of causing the collapse of larger stone and masonry structures.

  In fact, a fire seems to have caused the destruction of the entablature and the columns along the east-facing side of the portico, which were eventually replaced by a brick-and-rubble wall enclosing this corner of the famous facade.3 As a result, the exterior of the portico assumed the asymmetrical appearance that we see in countless images from the Renaissance, such as in Figures 1.7, 9.1, and 9.2. The new wall obscured the loss of the columns, provided support to the east side of the portico and pediment, and dramatically separated the portico from the piazza. Eventually this separation was exaggerated by the rising height of the piazza, from which it became necessary to descend by stairs to the level of the portico (see Fig. 1.4). The sixteenth-century antiquarian Flavio Biondo claimed that a visitor had to descend as many steps from the piazza to the portico as were once necessary to ascend in order to enter the temple in antiquity. It was a matter of seven steps in the seventeenth century.4 The damaged or missing columns and entablature were repaired or replaced in the seventeenth century in the course of two campaigns, as we shall see. Nevertheless, the threat of fire endured, as an anonymous nineteenth-century drawing of a forno (bakery) backed up to the rotunda testifies.5

  Urban VIII and the Pantheon

  Renaissance popes continued to attend to the maintenance of the Pantheon in various ways pertinent to their seventeenth-century successors, as will be seen throughout this chapter, but the record is sporadic. Under Paul II (1464–1471), for example, we know that masonry in the portico was repaired, as were the timbering and terracotta tiles for the roof.6 From this and many other notices pertaining to the piazza, we can be certain that the portico had a conspicuous place in the collective consciousness of Roman Renaissance antiquarians. Nothing more dramatically proves this fact than the outcry following the infamous despoiling of the bronze beams from the porch on the orders of Urban VIII Barberini in 1625. This incident gave rise to the well-known pasquinade satirizing the fact that a pope had dared to do what even the invading barbarians had never done – “what the barbarians did not do, the Barberini did” – quod non fecerunt i barberi fecerunt i Barberini. It mattered little that the bronze was later said to be destined for the casting of Bernini’s Baldacchino for St. Peter’s, rather than armaments for protecting the city.

  This episode, recently clarified by Louise Rice, is more complicated and interesting than previously thought. Presented with the need for additional cannon to protect Castel Sant’Angelo, Pope Urban VIII (1623–1644) authorized the removal of the ancient bronze beams that had been studied repeatedly and drawn very often in the course of the sixteenth century (see Fig. 9.15). The new research clarifies three aspects of the operation pertaining to our interest in the reception of the Pantheon. First, it is now clear that the despoliation of the bronze, originally intended for cannon, was soon justified by the report of its deployment to the Baldacchino in St. Peter’s, as a way to mollify Urban VIII’s critics. Evidently, the sacred destination for the bronze was deemed more acceptable to critics than the defensive purposes that inspired the operation in the first instance. In truth, not a bit of the metal can be documented in St. Peter’s, but it can be traced in the cannon of the period. So, in the reality of the day, defensive needs trumped antiquarian interests, but the antiquarian faction was not to be dismissed. This fact relates to a second revelation, namely, that the pope then embarked on a compensatory effort to restore the portico to its former glory, with significant results. Third, the operation inspired a debate about the original form of the portico’s vaulting and how it should be treated after the bronze beams were replaced by timbers. In Rice’s account, the removal of the bronze and its management from a public relations perspective reveal the depth of popular affection and erudite concerns for the ancient fabric in the seventeenth century.7

  The papal order for dismantling the bronze was issued in August 1625. The stated reason for the operation was to use the material for pezzi d’artegliaria (“pieces of artillery”) at Castel Sant’Angelo, but popular reaction was so swift that Urban VIII was immediately thrust into a defensive mode. By September, the Roman avvisi (news reports) attributed the pasquinade to Giulio Mancini, the learned Sienese doctor and author of a book on the art of painting. Although deeply concerned with the Pantheon, Mancini was also Urban III’s personal physician, and so there is good reason to attribute the pasquinade to candidates less dependent upon the pope. All the same, the result was a counteroffensive to justify Urban VIII’s orders and reestablish his good intentions. This is when he let it be known that the bronze would be used for a religious purpose, namely, the casting of Bernini’s Baldacchino, and from then on, the dual destination of the spoils was widely broadcast.8

  In fact, Rice calculates that 98 percent of the bronze was always earmarked for artillery, but because the material was brought to the foundry where both the Baldacchino and the papal cannon were manufactured, the pope’s intentions were effectively “camouflaged.” Those who knew of these matters recognized them as “a diversionary tactic,” as Rice terms it.9 Nonetheless, Urban’s compensatory repairs of the Pantheon exceeded pure necessity and added conspicuously to the appearance of the building. The bronze beams had to be replaced, of course, and careful drawings by Francesco Borromini demonstrate that considerable thought and skill went into the composition of timber substitutes, beginning with a detailed understanding of the ancient configuration (Fig. 10.1).10 In 1626–1627, Borromini also repaired the missing column on the northeast corner of the portico and provided it with a newly made capital. This capital can be easily identified by the Barberini bee that was carved on the flower of the capital (see Fig. 1.19). Even more conspicuous than the refurbished corner column was the addition of the two bell towers to replace the single tower that had to be dismantled to pull the bronze structures from beneath it. Drawings by Borromini for the design and construction of the towers survive to attest to the origins of these towers in the workshop of the chief papal architect of the day, Carlo Maderno (Fig. 10.2).11 The traditional but incorrect attribution of the towers to Bernini is ironic in view of the extensive rivalry between him and the Maderno-Borromini team. Could there be yet another level of dissimulation in the attribution of these new additions to the facade of the Pantheon, which were soon dubbed “the ass’s ears” (l’orecchie d’asino)? It is difficult to know for sure, but the unfounded relationship to Bernini expresses independently the extent to which both the towers and he were associated, for better and for worse, with the Barberini pope. Even in the modern archaeological literature the misattribution survives.12

  10.1. Truss work at the Pantheon; drawing by Francesco Borromini, 1625. (Albertina, Vienna)

  10.2 a and b. Inscriptions erected in 1632 by Urban VIII flanking entrance portal. (Photos author)

  The work accomplished by Urban VIII was memorialized on two large inscriptions flanking the bronze doors into the rotunda (Fig. 10.2). The tablet on the left alludes to the ancient bronze trusses, “a useless and all but forgotten adornment,” for the embellishment
of the apostolic tomb and the defense of the fortress of Hadrian (Castel Sant’Angelo). The tablet on the right refers to the pope’s restructuring of the roof and the construction of the twin bell towers. Both inscriptions were posted in 1632.13 In the years leading up to their appearance, while the Barberini distributed huge bronze bolts (pictured in Borromini’s drawing) from the ancient trusses as souvenirs, it is yet another irony that antiquarians busily debated the merits of completing a flat or vaulted ceiling in the portico in order to hide the trusses replaced in wood and to embellish the building in a manner befitting its heritage.14 Neither of theseplans was put into effect, but they reveal the ambitions of seventeenth-century thinking about an ancient Roman building.

  In both the old and the new roof system, the supporting members were braced on rough-finished masonry above the columns of the portico, which can be seen in photographs and drawings (Fig. 10.3). Nevertheless, the configuration of the ancient bronze trusses differed from their later wooden counterparts in a number of ways. The differences may be revealed to some extent by comparing Borromini’s scheme and any Renaissance drawings of the trusswork, although we must be careful to account for the variations in the latter that were not always done from on-site observation. In her analysis, Rice argues that the unusually compressed aspect of the ancient configuration may itself be an improvised solution devised in antiquity for a portico that was originally intended to be taller. This is an important suggestion because it is consistent with the theory of Mark Wilson Jones regarding a possible change in the size of the columns during construction. Thus, as a corollary to the suggested shift in the scale of the columns in ancient times, there would have been a concomitant change in the design for the trusses and the height of the roof of the portico.15

  10.3. Truss work in portico. (Photo author)

  The comparison of the ancient with the seventeenth-century truss systems could help us to envision the insertion of a barrel-vaulted ceiling under the ancient roof, whereas the Borromini scheme does not appear to leave adequate space for such a vault to span the wide central bay of the portico. In fact, the debate about a vault or a flat ceiling was ultimately left undecided and the project unexecuted, whether for lack of technical resolution, authenticity, or matters of funding. Two manuscript accounts of the issue survive to describe the considerations, one likely by the pope’s doctor, Mancini, the other anonymous.16

  As it happens, both authors endorsed the concept of a barrel vault over the central entrance axis. In the fashion typical of seventeenth-century dialectic, the objections are fully aired: false ceilings are more stable and cost less; the ancients never set vaults on columns; all vaults exercise lateral thrusts that would make them inherently unstable at the Pantheon; and resolving this instability with iron tie rods was unacceptable because the ancients never used them. To these objections, the anonymous author insists that vaults are stronger and more beautiful than false ceilings; that the ancients had indeed set barrel vaults on columns (and cites examples); that a properly constructed vault would produce no lateral thrusts; and that architects often make use of techniques unknown in antiquity. Both Mancini and the anonymous author agree that vaulting would complement the magnificence of the entire building, especially the dome. Mancini maintains that flat ceilings would compromise the portico’s airy dimensions, which had already been reduced by the accretion of soil burying the columns and portions of their shafts, no doubt referring to those bordering the piazza. In the end, no solution proved practical in the context of the new timbering for the portico, and so it remained – perhaps since the change in scale of ancient columns – an unfinished aspect of the most finished Roman building to come down to us, “a sort of ruin within a building otherwise intact,” in Rice’s felicitous phrasing.17

  Reading the Interior of the Pantheon

  In several brief but fundamental publications, Tilmann Buddensieg showed how the ancient Pantheon stimulated both admiration and criticism in the Renaissance and afterwards.18 Acknowledgment of the Pantheon’s design “faults” still comes as something of a shock because of our natural inclination to regard it as an authoritative model of ancient architecture for the early modern period. The truth is that over the centuries and right up to the present, scholars and architects have continued to observe some subtle but unusual, and sometimes inexplicable, features in the building whose character is anything but self-evident. Some of these features have been discussed in previous chapters in this book. Efforts to understand the structural realities and decorative logic of the Pantheon have been recorded since the fifteenth century and have continued to tease antiquarians into the eighteenth century and up to our time.

  Indeed, many of the difficulties in comprehending the edifice in the Renaissance were the same as those we face today: what explains the awkward formal connection between porch and rotunda, the apparent disjunction between paving patterns inside the rotunda and features of the elevation, or the apparent dissonance between the vertical lines of the main order, the smaller order in the attic, and the ribs of the dome? Observations on these issues and others have stimulated commentary in writings and drawings for centuries and compose some of the most sustained analyses and criticism in the whole history of architecture.

  A prominent catalyst for these commentaries was the attic zone of the interior, that portion of the elevation located between the entablature of the main order and the springing of the dome. For visitors then as now, it is obvious to see that the little pilasters, or pilastrini, of the attic are not consistently aligned with the grand Corinthian order rising from the pavement nor are they aligned with the ribs of the dome above them. (See Plates VII and X. For reasons mentioned in our Introduction (Chapter One), the pilastrini today survive in just a small section of the attic.) It appears as though this conspicuous portion of the composition of the Pantheon, a touchstone of ancient Roman architecture, violates a fundamental classical ideal, namely, that vertical components of an elevation be precisely aligned over one another, not partially and not over the void of a niche or in the middle of a bay.19 The assumed rule was: solid over solid, void over void.

  In the fifteenth century, Francesco di Giorgio Martini reconstructed the Pantheon in a drawing that appears to correct this apparent defect by inventing a second attic register and inserting it below the dome with a reduced number of pilastrini (Fig. 10.4). Moreover, he aligned his pilastrini with the ribs of the dome, in the process changing both the number and the position of the coffers.20 If Francesco’s were an isolated example of the phenomenon, we could attribute these features to inaccuracies generated by an artist working off-site or perhaps from a description, but this is just one of many examples of drawings and illustrations that consciously propose revisions to the composition of the ancient building.

  10.4. Project to refashion interior elevation of the Pantheon; drawing by Francesco di Giorgio, fifteenth century. (Biblioteca Reale, Turin, Saluzzo 148, fol. 80)

  To take a widely circulated example, we can turn to the printed treatise on architecture by Sebastiano Serlio. The illustrations appear in his Book Four, which was initially published in 1540 and is generally considered to be one of the first publications in architectural history to provide illustrations of a substantial canon of ancient buildings.21 The book illustrates the interior and exterior elevations of the Pantheon and includes many details. One of the details demonstrates how the woodcut alters the elevation so that the disposition of the main order, the small attic pilasters (the pilastrini), and the ribs of the dome are vertically aligned with one another, whereas this is not the case in the monument itself and never was (see Fig. 1.17). While purporting to present the interior of the Pantheon faithfully, Serlio has willfully “corrected” its composition to conform to his own expectations.22

  Antonio da Sangallo the Younger also engaged the issue of vertical alignments in annotated drawings that also take the ancient architects to task over the composition of the portico and the disposition of the columns within the buildi
ng (see Fig. 1.15). He draws attention to “another error” inside the Pantheon, which is that the pilastrini and the columns are not spaced uniformly and the upper pilasters do not fall uniformly over the orders below or coordinate above with the ribs of the vault, which he terms a “most pernicious thing.”23

  Not all Renaissance antiquarians and architects indulged in this sort of criticism, and few expressed themselves as clearly as Sangallo. In striking contrast to his drawings and commentary and to Serlio’s blatantly inaccurate illustrations of the Pantheon, Andrea Palladio’s illustrations of it faithfully record the monument as it stood, insofar as we can determine.24 His woodcuts accurately illustrate, for example, how the windows of the attic are located above each pier and each of the principal niches (see Fig. 1.18). He also faithfully captures the lack of vertical alignment between the pilastrini of the attic and the Corinthian orders that spring from the pavement. (Palladio’s detailed image of the elevation does not extend above the attic into the dome area, perhaps to avoid presenting the apparent “misalignment” of the dome’s ribs with the pilastrini and the principal order below them.)

  Possibly influenced by these concerns, some Renaissance architects preferred simply to omit the pilastrini of the attic when they drew the interior elevation of the Pantheon. In a beautifully detailed longitudinal section, Baldassare Peruzzi minutely annotated each feature with dimensions but leaves the attic unarticulated save for the windows located above each niche and pier (Fig. 10.5). Similarly, the transverse section of the drawing by Bernardo della Volpaia in the Codex Corner shows a blank attic, bare and uninterrupted but for its windows (see Fig. 9.19). While our sources do not explicitly reveal the reasons for omitting the pilastrini on these drawings, the architects would surely have been aware of the formal concerns we have mentioned. Could they have suspected, like many later observers did, that the polychrome revetment of the attic was added to the Pantheon when it was rededicated to Christianity? We cannot be certain.